feat: add exit-session skill

Runs the full /end-session workflow (session log, CONTEXT.md update,
doc refresh, git commit + push) then terminates the Claude process via
kill -TERM $PPID. Designed for automated shutdown scripts — no
interactive prompts.

skills/exit-session/SKILL.md

@@ -0,0 +1,64 @@
+---
+name: exit-session
+description: >
+  Run the full /end-session workflow (session log, CONTEXT.md update, doc refresh,
+  git commit + push), then terminate this Claude process. Designed for automated
+  shutdown scripts — no interactive prompts, exits unconditionally when done.
+allowed-tools: Read, Edit, Write, Grep, Glob, Bash(git log *), Bash(git diff *), Bash(git add *), Bash(git status *), Bash(git commit *), Bash(git push *), Bash(git stash *), Bash(date *), Bash(ls *), Bash(cat *), Bash(find *), Bash(rm *), Bash(mkdir *), Bash(sed *), Bash(python3 -m lib.cp_cli *), Bash(ssh-add *), Bash(kill *)
+---
+
+# Exit Session Skill
+
+**This skill is for automated shutdown. Run the complete end-of-session workflow,
+then unconditionally terminate this Claude process. No interactive prompts.**
+
+## Pre-gathered context
+
+### Session timestamp
+!`date +%Y%m%d-%H%M%S`
+
+### SSH agent keys (for pre-flight before push)
+!`ssh-add -l 2>&1 | head -5`
+
+---
+
+## Step 1: Run the end-session workflow
+
+Use the `Skill` tool to invoke the `end-session` skill. Wait for it to complete all
+phases (session log, state update, doc updates). Do **not** skip phases or ask for
+confirmation — run everything.
+
+## Step 2: Commit and push
+
+After end-session completes:
+
+1. Run `git status --short` to see what changed.
+2. If there are staged or unstaged changes to tracked files:
+   - `git add -u` (stage tracked modifications only — never `git add .`)
+   - `git commit -m "end-session: wrap-up [automated exit]"`
+3. Verify SSH key is present (`ssh-add -l`). If the relevant key appears, run
+   `git push`. If no key is loaded, **skip the push** and print:
+   `PUSH SKIPPED: no SSH key loaded — push manually after restart.`
+
+## Step 3: Terminate
+
+Run the following Bash command to terminate this Claude process:
+
+```bash
+kill -TERM $PPID
+```
+
+Do not output anything after this command. The process will exit immediately.
+
+## On any failure
+
+If end-session fails (disk full, parse error, etc.) or the push fails:
+- Print a one-line error summary
+- **Still run `kill -TERM $PPID`** — the shutdown must complete
+
+## Constraints
+
+- No interactive prompts — this runs during machine shutdown
+- Never block on user input
+- Complete within ~90 seconds where possible
+- If git operations time out (>30s), skip them and proceed to Step 3